Start-stop regenerative repeater



2 Sheets-Sheet June 28, 1949. P, PELLE START-STOP PEGENEATIVE REPEATERFiled May 9, 1945 w ,w a Z WN a r1v n m5 \l \|l \I E. W 2f .W m 1w e f1UO .n a f n n n f w r `f w P e r 0| llw 1111 a. i r u 4 --121 N 0/ I s TIR 5 m s t w/.R m s .I .1.11m ni z 5 iii-- l n y 4 d W E M v v 4 m w. /w4 U. w f/ 1.. J D .ma s l.l l -l il-, I f W ..H 11111:?? .C M 0l v t /.E2 12.1..- .nunwnnlnh v m. M n d r .M x 1 yk. ,0 i m 1m, .f i .J l r n w-uuh.; l l 0 1 i i l 0/ L. mr y o. H r

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June 28, 1949. P. PELLE 2,474,490

START-STOP REGENERATIVE REPEATER Fliled May 9, 1945 2 Sheets-Sheet 2Patented June 28, 1949 :STATE-s. "PATENT orifice Application May 191945, Seriall No. 592,770 In France February 10, y1944 Section 1, PublicLaw 690; August 8, 1946 Patent expires February 10, 1964 10 Claims. 1

The presentmvention relates to telegraph repeaters. and regeneratingAvand. distohtiQn eliminatingdevices for telegraph modulated signals sent`out in the arhythmigc-or start-stop code.

One ofthe obieetsofgthe presentinvention is to provide .a deviceL of thegeneral .character above referred ilo-comprising. mansior sendingcurrent impulses, said means beinggcontrolled by anl oscillater. therebyinsuring greater stabil-ity than has heretofore been. possible.

.Another` object of the present invention is to provide a device Vof thegeneraloharacter above described with novel inea-ns for insuring themarking or determination ci the. operating times withA precision.

These and such other aims and objects kof the present. invention as mayhereinafter appear will.y

be readily understoodf-romtlie following vdescrip-A tion, takenfin#connectionA with the accompanying drawing, of one illustrativeembodiment of the present invention.

It is known that when using disturbed tele-` graph lines or telegraphlinesy .of great length,l

the telegraph keying modulation oi the signal characterswwhichreaches.the receiving end ofthe line often suffers. considerable distortion,partien ularly when the line. is made of several sections, thetransmittingrelay for eachV section 'being connected tothe receivingrelay terminating a preceding section. I t is,l therefore, necessary toprovide devies tov correct such Vdistortions and reshape the distortedpulses constituting the elements of the signal. Various Iexpedients havebeenr usedr for this purpose.

.It is here proposed to use foreach group of the signal keyingmodulation received, a group of. short current impulses or signalelements precisely separated .from cach other by a unitary interval ortime element of' said modulations. This` group of shortcurrentimpulses'representing a charac-ter may consist, for example, ofseven such short impulses, if the code used is a-ve element code plus astarting and stop signal.

Suitable means are provided in the regenerating system of thefpre-sentinvention whereby the rst oi said current 'impuses occurs one-half of aunitary interval after the arrival of the starting signal element. As :aresult, the impulses that follow occur at mennen-.ts correspondingexactly to the mid-'point of the. theoretical intervals relative to eachelement of the code used. A device is provided-which receives. thesignal modulation tov be 11e-.shapedand.retransmittedy .and givespassage to 4short current impulses directed in the .same sense ordirccticnso that -iicw through 2 a winding of a polarizedrelay inone orthe other direction. .according tothe polarity ci the modulationsignalaelemenie received. at. the moment that said impulses arrivai Theshort current.irnpulses thus determine the instants when the armaturesof the polarized relay. are displaced er rocked, the'direction in whichsaid arnoatures.

are rocked being` determined by polarity of the signal element,neceivsed.h This polarized relaythus restores, the signal keyingmodulation which is received. tree of. distcrtimiy and with adisplacement-.of 'nimeer phase equal to one-.half oi theunitary.intemfal-v In the drawing:

Fig. 1 is. a bloei: diagram of the signal reeenerator system.;

Fie. 2 is adieercmshcwingthe; operating sequencek of the Severalsignal.elements as they occur in the regenerator;

Fig. 3 is a circuitoi; asystem incorporating the improvedsignalfregenerator for a telegraph line.

Generally speaking, the presen-t improved reer generator includesoscillator Whose frequency Y isaccurately adjustedso that` the length orperiod transmitted. oscillator is normally blocked.

but is instantaneously unblocked with a prede,-vr termined. initialphase upon thearrival of each starting` element of the received signalgroup. and aiterwar.dsl yblocked again,` responsive to the operation ofan impulse-counter at the theoretical instant which corresponds tothemid-point of the na-l steering signal element. cf thesignal group..assuming said stopping element to have a duration equal t0.` that, ofthe code elements of the Chaelatl' lseli.V

Qscula-tions.l thus generated cause a train (for eacnsierial group) of@sequence of short current impulses (Say seven. in. number) which,appeal?. at. a .particular peint, ci cach-cycley of the oscillatien-`andere consequently accurately spaced from one. another by a interval..The rst of, such oscillations has-its, positive. peak, due to a deviceadapted tc adjust. the oscillation phase, half a unitary interval afterthe arrival cf the starting signal element.; IIt follows thatthesubsequentimpulses appear .at instants which exactly correspond withthe Iiidvpoint of theoretical intervals ci cach codesisnal. elerrient.4

A current reversing device is provided for receiving the incoming keyingmedir.lated signal t0 be regenerated or recharged and yfor allowingpassage of short current impulses which all have the same direction, insuch manner that thelr flow through the winding of a relay in eitherdirection, depending upon the polari-ty of the received signalmodulation element as they arrive.

The short current impulses consequently determine the displacement yorrocking times or instants of the armature of the relay, the direction ofthe rocking action being dependent upon the received polarity of thesignal element. Such polarizd relay restores or re-shapes Without anydistortion the elements of the rceived signal train and with a time lagequal to half a unitary interval of the signal element. As a result ofthis, it corrects both the irregular distortion and the rate of keyingmodulation. The maximum distortion of the received modulation signalthat can be possibly regenerated or reshaped, is limited only by theduration of the short current impulses or elements. The latter should belong enough to actua-te the polarized relay.

In the system of Fig. 1, the modulation of the keyed signal received onthe incoming line L1 operates an input relay RE, the duty of which is toblock or unblock an oscillator O. Oscillations delivered by thisoscillator ow to a phase shifter D and control a short current pulseshaper or emitter I. Such pulses or impulses, as well as the modulationof the keyed signal received by the incoming line L1, are applied tocurrent reversing means which may illustratively comprise a set ofrectifying cells RS associated with a polarized output relay R. Theregenerated modulation constituting the keyed signal is delivered at theoutput from reverser RS on the outgoing line L2. An impulse counter CIcounts the impulses delivered by the emitter I and, as the seventhimpulse occurs, releases the input relay RE, thereby blocking theoscillator O, and resumes its unoperated position.

In Fig. 2 are representedthe operating instants or times of the severalelements of the system.

' At (a) in Fig. 2, is shown the perfect signal elements of a typicalseven element train or group, representing a letter, as emitted by atransmitter at the of an incoming line L1.

At (y) and (h) in Fig. 2, are shown extreme possible types of distortedsignals arriving at the repeating regenerating station and applied toinput relay RE and also direct to the winding of polarized output relayR, which distorted signals can be reconstituted into the originallytransmitted perfect signal of Fig. 2(a) by the regenerator heredescribed, as can likewise received signals whose elements are lessseriously distorted.

Fig. 2 shows at (b) the movements of the armature of input relay RE.which closes, after a brief operating interval, after the arrival ofnegative initial starting impulse d, and remains closed until there havebeen counted, as by condenser storage, six following impulses, the lastbeing the stop impulse (a) ofl positive polarity which deenergizes inputrelay RE. During the time that input relay RE is thus closed, as shownat Fig. 2(1)). it unblocks oscillator O of the keying element frequency,which over the same period of time delivers oscillations as shown at (c)in Fig. 2. The phase of these oscillations is shifted so that. as shownat (d) in Fig. 2, the peaks are the mid-point of the interval of each ofthe signal elements.

Short pulses, as shown at (e) in Fig. 2, are formed by a pulser on thepositive peaks of the of the modulation signal keying element.

phase-shifted oscillations shown at (d) in Fig. 2, and are applied totime a pole-changing output relay in accordance with the polarity ofincoming signal elements, producing outgoing signal elements, as shownat (j) in Fig. 2, which are the same as the perfect signal elementsshown at (a) in Fig. 2, but shifted by one-half of the length of thesignal element.

In Fig. 2, is shown at (a) by way of example, any perfect modulationsignal as received on the incoming line L1 and corresponding to acharacter. T is the duration of the unitary time interval of the signalcode, the changes in the current direction occurring at the instantsdesignated by T, 2T, 3T, 4T, 5T. The initial and final signal elements dand a are, respectively, the starting and stopping elements for theparticular signal group, while the signal elements I, 2, 3, 4, 5, arethe code elements representing a letter or gure. Fig. 2 also shows themovements of the armature of the input relay RE. `This relay being inunoperated condition at the instant taken as zero time, its armaturewill be rocked on arrival of start element d, so that the osciliator Ois unblocked a very short time O1 (Fig. 2-d) following the arrival ofthe starting initial signal element d. Oscillations as applied by theoscillator O are represented at (c) in Fig. 2. After passing through thephase shifter D, they appear as shown in Fig. 2 at (d), each minimumcorresponding to the instants T, 2T, 3T, and so forth, while eachmaximum corresponds to the midpoint of a modulation or keying element.

The pulse sender I delivers a short current pulse at each peak ormaximum of the oscillations in the output of the phase shifter as shownat (e) in Fig. 2. The positions assumed by the armature is of the doublecurrent polarized output relay R are illustrated at (f) in Fig. 2.Normally this armature is pulled from its left contact r3 to its rightcontact t3 when the rst short current pulse reaches relay R, thedirection in which said pulse flows through the exciting Winding of therelay having been predetermined by the polarity (Fig. 2--a.) As thesecond short impulse of the group of seven constituting the letter,reaches output relay R, it oWs through the winding of polarized relayRin the reverse direction, since the polarity of the modulation keyingsignal element I is the opposite to that of initial starting signalelement (d) and rocks the armature of relay R into contact with its leftcontact r3. The same phenomena occur for the other impulses of the groupof seven shown in Fig. 2-a, constituting the letter. The fifth impulsefor the character shown in Fig. 2-a has no effect on the output relay Rbecause of its tendency to rock its armature into Contact with the leftcontact 1'3 against which it has been previously brought by thepreceding impulse.

The seventh impulse counted by the impulse counter C'I returns the inputrelay RE to rest position and blocks the oscillator O. The input relayRE operates very fast in returning to its rest condition.

As will be seen, keying signal elements of a received signal, althoughconsiderably distorted as those shown at (y) and (h) in Fig. 2, willstill be correctly regenerated or reshaped since the polarity of theelements of the output during intervals of the pulse with O2 duration(Fig. 2 6) which correspond'to the several pulses, are similar to thoseof the corresponding elements of the 5 perfect. modulation of thertransmitted signal, as. shown` aty (a) in Fig. 2.

Fig. 3. shows an illustrative possible, applicationy of a Vdeviceembodying the present invention. As shown in thisembodiment, the doublewinding inf-z put relay RE has two diierential windings I, 2, of which 2is the weaker, the winding I being connected on the one hand to theincoming line L1 and on the other hand to a current source +B..

The winding 2 of input relay RE is in the cir*- cuit of the pulsecounter CI, and input relay REy is provided with a pair of armatures i1and i2 in operative relation with the windings I", 2, of irrputv relayRE, said armatures vibrating through the gaps between contacts rl, tI,and r2, t2, respectively.

In unoperated position, the armature ii rests on. contact r1 while thearmature i2 rests on contact 12. Should a signal element of positivepolarity` be received on the incoming line L1, no current will flowthrough the winding I of input relay RE, this polarity being nullii'ledby the positive current source -I-B. The oscillator O of thecapacityresistance type is then blocked, the condensers C1, C2, C3, ofits grid circuit being charged.y through contact r1 with a predeterminedpositive voltage by a potentiometer P1, so that their charge shall equalthat corresponding to the peak of the oscillating plate voltage of theoscillatorI tube O when oscillating normally.

When relay armature i1 is in rest position en,- gaging contact r1, thereis no coupling between,l the plate circuit and the grid circuit of theoscil-A lator tube O, so that this tube cannot oscillate and is blocked.When armature i1 is in operated position engaging Contact t1, there iscoupling between the plate circuit and the grid circuit of theoscillator tube, through condensersl CI, C2, C3, and the tube isunblocked. and oscillates.

The impulse counter CI is constituted by a circuit including acapacitance 3. and a cathode re.l sistance l associated with a gasdischarge tube. When the armature i2 of the input relay RE is onrestcontact r2, the grid I5 of the discharge tubeV has cathode potential,whereby this discharge tube becomes conductive and closes a circuitacross the capacitance 3 between the positive ter'- minal of battery HT,and the grounded negative terminal of battery HT. The current throughthis circuit flows through the differential Winding 2 of the input relayRE and holds its armatures in contact with the contacts r1 and rz, underwhich circumstances they are unoperated position. Thus, when the firstcharging impulse is applied to condenser 3, oscillator I remains.`blocked.

Upon the arrival of the starting element d of a signal train, a negativepolarity exists on the line L1, current ilows from +B, and the principalwinding I of the input relay RE is energized. The action of this WindingI, is stronger than that of the diierential winding 2 of input rel-ayRE,v whereby the input relay RE rocks its armatures ii and i2 intocontact with actuated contacts t1 and t2, respectively. Owing to theContact madec at t1 the oscillator O is unblocked and the oscillan tionstarts instantaneously owing to the charge which was delivered throughContact t1 to the capacitances C1, C2, C3, of the grid circuit duringthe unoperated period, which charge corresponds to the voltage which isthe peak plate Voltage of oscillator tube O during norm-a1 operation.The-f initial phase of the oscillation corresponds to the.y

6r" ofthe discharge tube of the impulse. counter ci? is connected atAoperated.' contact ti to apoten-tial. determi-ned by a. potentiometerP2, whereby it is negatively polarized 'withy respect to the cathode .ofsaidv tube as determined by the cathode resista ance 4. The gastube ofthefimpulse counter then ceases tobe conductive, and the capacitance3Lis:

sldwly charged ironia; current. source l+HI.

lEhe oscillation delivered; from` oscillator O flows :through the phaseshifter Dr constitutedy byv the capacitancef-andthe resistanceslsand'I-; itl trips; thepulse sender l': constitutedby a triode-pentode.

conl'iccteclv asisvknown. in the art to'fform a blocki ingy relaaiation`oscillator by' a double' coupling be-A tweenv the pent-ode grid and thetriode plate ort the onehancl., andvv to. a. cathode resistance 8 onsthe otherhand.v Pulses collected in the pentodeplate,V circuit passvthrough transformers 9, t3: Each impulse as it passes through thetransformer Ill'. transientlyrenders the grid of the gas'. dischargetube of impulse counter CI more pos'ie tive, thereby approximating thevalue'. of its potential; to. that ofrthcfcathode. The time constant ofthe circuitv including the; capacitance 3., and: resistance 4 is.. socalculated that the scvenl'fllz` impulse renders the gasy tube of CI;condlmting-iv At this moment,` the dischargecurren-t froml the:lca'pac-:itmncev 3 passes. through the win-ding 2'. op the input relayRE. and returns the armature of,

RE tounoperatedposition, closing;l contactsri andv r2, thereby blocking;oscillator O.

As they flow through the transformer 9`r ther short current impulsesreach thesetv of rectiyingl cel-ls Il, I2, I3, I4, constitutingl currentreverser RS associated with the polarized. output rela-y Re thearmature* is of which comprises a permanent magneti and is connected tothe-outgoing line Lz. and can beI rocked into Contact with either one o;the relay contacts trend r3, which are respec-y tively connected` to thetelegraph line batteries,- -I-B and -B. When current iloWs through. the;twov windings in series'. of relayR in one direction, the armatureis.Vrocked into engagement with relay contact 1jr-if; it` is not alreadyinengagement. therewith. Whenl current flows through the two# windingsin series of relay R in the oppositev di-` rection, the armature isisrockedintoen'gagement with` right contact .tai-f' it is not already inengage men-t therewith.;l The armature is is usually'in engagement with4eitherv ra or ta, depending on the directionv o the last pulse ofcurrent through the;-` Windings of relay The setof rectifying cells,RSfis. of known construction; and arrangement.. andN comprises the fourrecti-fying cells, I I, I-2f,` I3g,-,

55, t4. When. a positive polarity,A is applied to the incomingA line.L1, cl-irrentsL iiow through the;k transverse rectiiier cells I 2 andI3\ and render themconductive.` These currents. have no actionf whateveron the` output relay R, the current;

mi tl-irougghv one ofthel two windings I and 2 of the;v

latter tloWi-ng the opposite direction to thatpf the currentiiowingthrough the other.- If, dure.` ing the moment when cells I2 and I3 arethus; rendered conductive\,V a pulse fromemitter I flows throughthetransformer 9, it nds-aconductiyepat-h throughthe-f conductive-yrectifying cells I2*L and L3 and the two windings I=, 2,- of the output.relay Rif which are connected in series,l whereupon, this relay rocksYits'. armaturen i'ntocontact with A 'mi theleit contact mi anda positivepolarity is imzpeak ofv thel plate voltage. (Fie. 2.-:2.)v The grid. tcmoment; ar'nulse.; from @mit.ter-k I. passes through.

the transformer 9, it will ow through the rectifier cells I I, I4, andthrough the output relay R, but in the reverse direction. The outputrelay R then rocks its armature i3 into contact with right contact t3and a negative polarity is imparted to the outgoing line L2. As will beseen, distorted impulses arriving through the incoming line L1 cannotalone control the output relay R, the latter responding only to correctimpulses furnished by the unit O, I, 9, which is determined by theoscillator. Signals sent through the outgoing line Lz are consequentlyof correct shape.

I am aware that the present invention may be embodied in other specicforms without departing from the spirit or essential attributesthereof,l and I, therefore, desire that the present embodiment of theinvention be considered in all respects as illustrative and notrestrictive, reference being 'had to the appended claims rather than tothe foregoing description to indicate the scope of the invention.

What is claimed is:

1. A regenerating and distortion-eliminating device for telegraphicmodulated signals emitted in the start-stop code, comprising on atelegraphic line an oscillator having a period equal to the theoreticalduration of the unitary interval of the modulations requiringregeneration, an input relay located before said oscillator for blockingand unblocking the oscillatorLe, phase shifter fed by the oscillator, ashortcurrent vimpulse emitter tripped by said phase shifter, a currentreversing device and polarized relay unit fed by said emitter andformingthe output terminal of the regenerating and distortion eliminatingdevice, and means shunted across the input relay and emitter forcounting the impulses generated by said emitter and lfor actuating theinput relay to block the oscillator while itself resuming itsinoperative condition at the appearance of the seventh impulse of aSequence. l

2. A regenerating and distortion-eliminating device for telegraphicmodulated signals emittedv in the start-stop code, comprising on atelegraphic line an oscillator having a period equal to the theoreticalduration of the unitary interval of the modulations requiringregeneration, an input relay connected in the input of said oscillatorfor blocking and unblocking the oscillator, a phase shifter fed by theoscillator, a short' current impulse emitter tripped bysaid phaseshifter so as to center each impulse on the theoretical mid-points` ofthe several codeelements, a current reversing device and polarized relayunit fed by said emitter and forming the output terminal of theregenerating and distortion eliminating device, and means shunted-across the input relay and emitter for counting the impulses generatedby said emitter and for operating the input relay to block theoscillator while itself resuming its inoperative'condition at theappearance of the seventh impulse of a sequence.

-l 3. A regenerating and distortion-eliminating device for telegraphicmodulated signals emitted in the start-stop code, comprising on aAtelegraphic line an oscillator having a period equal t'o thetheoretical duration of the unitary interval of the modulationsrequiring regeneration, an input relay located before said oscillatorfor blocking and unblocking the oscillator, a phase shifter fed by theoscillator, a short current impulse emitter tripped by said phaseshifter, a current reversing device and polarized relay unit fed by saidemitter and forming the output kterminal of the regenerating anddistance eliminating device, r

said reversing device comprising a rectifier bridge and determining thedirection of flow of said impulses through said relay responsive to thepolarif?. ties of each code element as received when the impulseappears, and means shunted across the input relay and emitter forcounting the impulses generated by said emitter and for operating theinput relay to block the oscillator while itself re- 10 'suming itsinoperative condition at the appearance of the seventh impulse of asequence.

4. A regenerating and distortion-eliminating device for telegraphicmodualted signals emitted in the start-stop code, comprising on a telefgraphic line having an input terminal and an output terminal, anoscillator having a period equal to the theoretical duration of theunitary interval of the modulations requiring regeneration, an inputpolarized relay connected in the input of said oscillator for blockingand unblocking the oscillator, said relay including a pair ofdifferential windings and armatures, one of the windings interconnectingthe line input terminal and a current source, a phase shifter fed by theoscillator,

a short current impulse emitter tripped by said phase shifter, a currentreversing device and polarized relay unit fed by said emitter andforming the output terminal of the regenerating and distortioneliminating device, and an impulse counter including the other inputrelay winding for counting the impulses generated by said emitter andfor actuating the input relay to block the oscillator while itselfresuming its inoperative condition at the appearance of the seventhimpulse of a sequence.

5. A regenerating and distortion-eliminating device for telegraphicmodulated signals emitted in the start-stop code, comprising on atelegraphic line an oscillator of the capacitance- 4U@ resistance typehaving a period equal to the theoretical duration of the unitaryinterval of the modulations requiring to be regeneratedan input relayconnected in the input of said oscillator for blocking and releasing theoscillator, a

phase shifter fed by the oscillator, a short current impulse emittertripped by said phase shifter, a current reversing device and polarizedrelay unit fed by said emitter and forming the output terminal of theregenerating and distortion eliminating device, and an impulse counter'bridging the input relay and emitter and comprising a condenserconnected for storing pulses emitted by said pulse emitter for countingthe impulses generated by said emitter and being connected for actuatingthe input relay said inin the start-stop code, comprising on atelegraphic line, an oscillator of the capacitanceresistance and tubetype including grid circuit condensers positively charged bypotentiometer means, said oscillator having a period equal to thetheoretical duration of the unitary interval of the modulationsrequiring regeneration, an input relay connected in the input of saidoscillator for blocking and unblocking the oscillator, a phase shifterfed by the oscillator, a short current impulse emitter tripped by saidphase shifter,

a current reversing device and polarized relay unit fed by said emitterand forming the output terminal of the regenerating and distortioneliminating device, and an impulse counter bridging the input relay andemitter and comprising a condenser connected for storing pulses emittedby said impulse emitter for counting the impulses generated by saidemitter and being connected for actuating the input relay, said inputrelay being connected when actuated to block the oscillator.

7. A regenerating and distortion-eliminating device for telegraphicmodulated signals emitted in the start-stop code, comprising on atelegraphic line an oscillator having a period equal to the theoreticalduration of the unitary interval of the modulations requiringregeneration, an input relay located before said oscillator for blockingand unblocking the oscillator, a phase shifter fed by the oscillator, ashort current impulse emitter tripped by said phase shifter, a currentreversing device and polarized relay unit fed by said emitter andforming the output terminal of the regenerating and torsion eliminatingdevice, and an impulse counter bridging the input relay and emitter andcomprising a condenser connected for storing pulses emitted by saidimpulse emitter for counting the impulses generated by said emitter andbeing connectedA for urging the input relay, said input relay beingconnected when actuated to block the oscillator, said counter includinga capacitance and resistance unit associated with a discharge tube.

8. In a telegraph repeater regenerating system transmitting signaltrains of signal elements of both polarities of uniform durationdetermined by a definite keying frequency including initial starting andnal stop elements, an input relay having a principal winding and anopposing bias winding, an output polarized relay having two windingsconnected in series and having two controlled contacts, connectedrespectively for applying voltages of opposite polarity to its armature,a line input terminal connected to the common terminal of said windingsof said output relay and also connected to said principal winding ofsaid input relay, a blocking oscillator tube of said keying frequencyand having its blocking circuit connected to a controlled contact ofsaid input relay for becoming unblocked y upon receipt of a start pulseby said input relay, a phase shifter connected to the output of saidoscillator tube, a narrow pulse former connected to the output of saidphase shifter and adapted to form a narrow pulse on the positive peaksof the output of said phase shifter, a rectifier bridge having twoterminals connected to the output of said pulse :former and having itsother two terminals connected to the outer terminals of the `windings ofsaid output relay, said rectifier bridge having only one of its pairs ofarms conductive at a given time as determined by the polarity of thesignal element applied at a given instant to said line input terminal,whereby the direction of application of pulses from said pulse former tothe two windings in series of said output relay is determined by thepolarity of the instantaneous signal element applied to the inputterminal, and regenerated undistorted signals are delivered to thearmature of said output relay.

9. A system according to claim 8, and an irnpulse counter unitcomprising a gas triode and a condenser, said condenser being connectedin the output circuit of said gas triode through said biaswinding ofsaid input relay, controlled contacts of said input relay connected forconnecting the grid of said gas triode to its cathode when saidoscillator is blocked and for connecting Said grid of said gas triode tothe output of said pulse former when said oscillator is unblocked, saidoutput circuit of said gas triode including said condenser being adaptedupon the receipt from said impulse former of the number of signalelements constituting a complete Signal train including the final stopelement, to cause said condenser to discharge and ionize said gas tubeand actuate said input relay to stop said oscillator.

10. A system according to claim 8, the blocking circuit of said blockingoscillator comprising reactive elements adapted to initially apply tothe plate of said blocking oscillator tube at the instant of unblockinga positive Voltage which is the peak voltage of said lblockingoscillator tube during normal operation, whereby upon unblocking thesaid oscillator tube starts its initial oscillation at its normalpositive peak,

PELLE, PIERRE.

REFERENCES CITED The following referenlces are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,133,456 Kinkead Oct. 18, 19382,357,840 Martin Sept. 12, 1944

